1. Field of the Invention:
This invention relates to cameras with automatic focusing devices whose operations are controlled by the electromagnetic force exerted on an electromagnetically driven shutter.
2. Description of the Prior Art:
U.S. Pat. No. 4,243,309 and U.K. Pat. No. 2,016,155A disclose cameras in which a single electromagnet provides the force for performing automatic focusing operation (hereinafter "AF" operation) and a shutter blade opening and closing operation. However, such conventional cameras use a control member to start a motion and stop the motion at the focused position when the electromagnet is energized and de-energized during the AF operation. This requires accurately sensing the position of the control member during motion. Also, such conventional camera need to arrest the moving control member accurately in the focused position. This requires adjusting each mechanism by taking into account the lag of the actuation, or the lag from the moment the focus detecting means produces an actuating signal to the moment the control member is stopped by the electromagnet.
Therefore, prior art cameras were disadvantageous because of the need for the fine adjustment in each of the coordinated mechanisms. This is particularly true regarding the relationship with the shutter mechanism.